Apparatus for drilling boreholes



Feb. 1, 1955 T. v. MOORE APPARATUS FOR DRILLING BOREHCLES Filed Aug. 29, 1950 Thomas V mqore/ Gnvengbor b s LO Gabon-neg United States Patent 2,701,123 APPARATUS FOR DRILLING BOREHOLES Thomas V. Moore, Manhasset, N. Y., assignor to Standard Oil Development Company, a corporation of Delaware Application August 29, 1950, Serial No. 182,005 2 Claims. (Cl. 255-19) The present invention relates to an improved apparatus for drilling well bore holes. The invention is concerned with an improved high speed rotation method for drilling well bore holes utilizing a novel rotary bit assembly. In accordance with the present invention an improved speed multiplier is employed in conjunction with a rotary bit whereby a high speed of rotation is obtained on the bit while using a conventional speed of rotation of the pipe string.

In the exploration for oil the art of drilling well bore holes into subterranean areas of the earth has been widely investigated and extensively developed. The techniques employed are many and a wide variety of drilling bits and associated apparatus have also been developed. One conventional procedure is to attach a suitable bit on the end of a pipe string and to rotate the bit by the rotation of the pipe string. By this procedure it is obvious that the speed of rotation of the bit is equal to the speed of rotation of the pipe string. Moreover, generally speaking, a conventional technique for applying the required force to the bit is to allow the weight of the drill string to partially rest on the bit. This is not entirely satisfactory since it is often desirable to secure a relatively high speed of rotation of the bit, but this is prevented by the various difliculties encountered when rotating a relatively long pipe string in a rapid manner. For instance, the pipe string tends to wind up resulting in stresses which tend to increase the corrosion rate. Also the pipe string tends to buckle and weave, often hitting the wall of the well causing non-uniform operations.

It has now been discovered that relatively high speed of rotation of the bit may be secured providing the novel device of the present invention be employed. The invention consists essentially of a planetary gear train in which the planet gear frame is held stationary by suitable dogs. Axial water courses through the planet gears provide for the proper mud circulation in order to secure the desired removal of the rock chips.

The present invention may be readily understood by reference to the drawings illustrating embodiments of the same. Figure 1, a section on line I-I of Figure 4, is a diagrammatical sketch of the high speed bit assembly. Figure 2 comprises a section taken through IIII of Figure 1, while Figure 3 comprises a section through IIIIII of Figure 1, and finally, Figure 4 comprises a section through IV-IV of Figure 1.

Referring specifically to Figure 1, the bit assembly comprises an outer case 1 attached to the lower end of a pipe string 20. The inner surface of case 1 is smooth at points 8 and 9 to allow for the relative movement of the mud packing. Between points 8 and 9 the inner surface of case 1 is machined to form a ring gear as shown in Figure 2. The planet gear case comprises an upper plate 2, the lower gear frame 3, a lower plate 2', and the planet gears 4, as shown in Figure 2. The lower plate 2 may be pinned to frame 3 or may be integral therewith. The planet gears turn on bearings suitably sealed against the entrance of high pressure drilling mud and are drilled axially to provide water courses 4a which connect the upper mud chamber 10 with the lower mud chamber 11. Dogs 6 are provided in a suitable recess in the planet gear frame as shown in Figure 4. These dogs under the influence of centrifugal force move outwardly and engage the walls of the hole being drilled. This holds the planet gear frame and prevents rotation.

Gear A is an extension of the bit body 5B. The lower part of the bit body is adapted to hold the cones 12 of the conventional jet rock bit in a customary fashion. The proportion of the gears are such that when the planet gear case is locked against rotation the sun gear 5A 2,701,123 Patented Feb. 1, 1955 rotates with a velocity substantially higher than that of the ring gear. Conventional jet water courses 7 are drilled through the body of the bit.

In operation when the drill pipe and bit are run to the bottom of the hole, rotation of the drill pipe causes the dogs 6 to move outwardly and engage the walls of the hole being drilled. As soon as the planet gears are prevented from rotation about the sun gear, the sun gear which is an integral part of the bit body rotates with a higher velocity than that of the ring gear which is made up to the drill collar. Thus, in actual operation, drill pipe 20 rotates, thereby rotating the ring gear machined on the inner portion of the case 1 attached to the drill string. Dogs 6 hold the planet gear case fixed with respect to the bore hole, maintaining the axis of the planetary gears stationary with respect to the bore hole. Rotation of the ring gear therefore causes the planet gears to rotate on their own axes. In turn, the planet gears act to rotate the sun gear associated with the bit body at a greater rate of speed than the drill pipe. The bearings illustrated permit weight to be placed on the drill bit while applying the stepped up rotational speed to the drill bit as described. The mud courses, aided by the packing illustrated, permit mud to flow through the drill pipe, and through the mud courses of the planet gears to the drill bit.

The present invention is generally concerned with a bit assembly whereby the speed of rotation of the bit may be increased in an efiicient manner. The bit assembly comprises a ring gear, planet gears, and a sun gear. The planet gears contain water courses through which the mud flows, thus, enabling the teeth surfaces of the gears to be set in grease or other satisfactory lubricant. In conventional operations, the speed of rotation of the pipe string may vary from 60 to 400 R. P. M. The preferred speed of rotation for eflicient operation is in the range from about to R. P. M. The gear ratios are set so that the speed of rotation of the bit, as driven by the sun gear, is from 2 to 4 times, preferably about 3 times the speed of rotation of the pipe string.

Having described the invention, it is claimed:

1. Improved high speed of rotation bit which comprises an outer case assembly, the inner surface of which is machined to form a ring gear, said outer case assembly being adapted to be affixed to the lower end of a pipe string, a planet gear frame having a body portion positioned below said ring gear including an upper plate member positioned above the ring gear and a lower plate member positioned below the ring gear, planet gears rotatably fixed in said upper and lower plate members of the gear frame to mesh with said ring gear, said outer case assembly having a central cutaway portion above the said ring gear providing a chamber above the planet gears in fluid communication with the interior of the pipe string, said body portion of the planet gear frame having a central cutaway portion below said ring gear providing a chamber below the planet gears, axial fluid passages in said planet gears in fluid communication with said upper and lower chambers, a plurality of dogs pivotally mounted in said planet gear frame adapted to engage the bore hole wall, a bit body dependent below said planet gear frame, a sun gear centrally fixed to said bit body and extending upwardly from the bit body through said planet gear frame to mesh with said planet gears resulting in high speed rotation of said bit body on slower rotation of said pipe string, and mud passages through said bit body communicating with said lower chamber.

2. Apparatus as defined by claim 1 wherein the gear ratios are adapted to rotate the bit driven by the sun gear from two to four times the speed of the rotation of the pipe string.

References Cited in the file of this patent UNITED STATES PATENTS 160,877 Chapman et a1 Mar. 16, 1875 1,894,039 Hill Jan. 10, 1933 1,944,838 Hill Jan. 23, 1934 2,151,646 Subkow et al. Mar. 21, 1939 2,528,300 Degner Oct. 31, 1950 

